Publications by Andreas Seifert

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Ferroelectric capacitive devices for memory and MEMS applications require patterned ferroelectric thin films with high anisotropic etched features. In this paper, physical and chemical parameters during etching of Pb(Zr0.53Ti0.47)O-3 (PZT) by a dual frequency ECR/RF reactor have been investigated. The removal characteristics of blanket films and films with a patterned mask were investigated as a function of gas chemistry (Ar, halogen gases), substrate bias RF power and working pressure (from 5 x 10(-4) Pa t

Pb(Mg1/3Nb2/3)O-3 thin films were prepared from modified alkoxide solution precursors and their dielectric and electromechanical characteristics were investigated. Preparation of the films is very sensitive to processing parameters. The influence of different seeding layers on the microstructures is discussed. Films show relaxer-like behavior, but with dielectric permittivity which is low (4500 at peak) compared to bulk ceramics and single crystals. Large electric de bias fields (up to 120 kV/cm) can be app

The properties of Pb1-xCaxTiO3 (x=0-30) thin films for applications in point-detectors and arrays can be further improved ii porous, low-dielectric constant layers are being Used. Both 2-methoxyethanol and 1,3-propanediol based solution precursors were used for spin-coating platinized Si3N4/SiO2/Si wafers. The heating-rate during the final anneal was observed to be the controlling parameter for the evolution of either dense or porous microstructures, Low temperature crystallization of the perovskite phase (

Pyroelectric thin film 12-element linear arrays (element size 0.4x0.9 mm(2)) have been fabricated by standard photolithography techniques on silicon substrates. A voltage responsivity of almost 800 V/W in air and 3000 V/W in vacuum is measured at low frequencies (0.1-1 Hz). Measurements are compared to finite element simulations. Doping of lead titanate thin films have been studied. Incorporation of porosity and Ca-doping of lead titanate thin films was found to improve significantly the pyroelectric proper

Poling of calcium and zirconium modified lead titanate pyroelelectric thin films has been studied, Poling temperature and electrical field were optimized to achieve high figure of merits. It was found that thermal activation is important to obtain highly poled films. Defect-dipole complexes are supposed to play a major role to retain the polarization and also to enhance it. Porous calcium substituted films achieved an up to three times higher voltage response than zirconate substituted thin films, because p

Pb1-xCaxTiO3 thin films with x = 0-0.3 for pyroelectric applications were deposited on platinized silicon wafers by chemical solution processing. Ca-substitution for Pb in PbTio(3) results in a reduced cia ratio of the unit cell, which, in turn, leads to better pyroelectric properties. Control of nucleation and growth during rapid thermal annealing to 650 degrees C allowed the formation of either highly porous or dense (111) oriented films. The inclusion of pores creates a matrix-void composite with the low

Piezoelectric coefficients and electric field-induced strains are investigated in Ca-modified PbTiO3 (PCT) films deposited by sol-gel technique. The microstructural evolution and related electromechanical properties are studied as a function of Ca content and porosity of the films. The porosity is tailored by changing the heating rate during the final crystallization anneal. It is found that piezoelectric properties of porous films heated at slow rates are superior to those of dense films crystallized using

Pb(Mg1/3Nb2/3)O-3 (PMN) alkoxide precursor solutions were synthesized and used to prepare thin layers on TiO2/Pt/TiO2/SiO2/Si substrates by spin coating. Many parameters like homogeneity of the solution and appropriate processing must be controlled to minimize the pyrochlore formation. Optimization of the processing allowed highly (111)-oriented thin films to be obtained. Dielectric measurements and TEM investigations were performed and showed that PMN thin films exhibit relaxer behavior.

The pyroelectric properties of Pb1-xCaxTiO3 (x = 0-0.3) thin films have been greatly improved by including porosity in the microstructure. Control of nucleation and growth by variation of the heating rate was used to process porous, low dielectric constant films on platinized silicon wafers. Electrical characterization of poled films showed pyroelectric coefficients of up to similar to 200 mu C/m(2) K and permitivities as low as epsilon(r) approximate to 55. The resulting high figure-of-merit p/epsilon(r) i

The effective piezoelectric coefficient e(31) has been measured on sol-gel processed Pb(ZrxTi1-x)O-3 thin films with Zr concentrations ranging from 45 to 60%. The largest value was observed at 45% Zr, although dielectric constant and effective d(33) peak at 53% Zr. The findings suggest that the optimal composition for microactuators and sensors is less than or equal to 45% Zr, i.e., in the tetragonal part of the phase diagram.

Pb(Zr-x, Ti1-x)O-3 (PZT) piezoelectric thin films are of major interest in MEMS technology for their ability to provide electro-mechanical coupling. In this work, the effective transverse piezoelectric coefficient e(31,f) of sol-gel processed films was investigated as a function of composition, film texture and film thickness. Dense, textured and crack-free PZT films have been obtained on silicon substrates up to a thickness of 4 mum. Crystallization anneals have been performed for every 0.25 mum. Nucleatio

New micromachined pressure sensors based on PZT coated silicon cantilevers have been fabricated and integrated in a photoacoustic gas detector. PZT Sol-gel thin films texture and composition were optimized with respect to the transverse piezoelectric coefficient e(31,f). A best value of -12 C/m(2) was obtained with (100)/(001) textured thin films at the MPB composition. Optimum stress compensation between the different layers composing the cantilever has been studied in order to yield flat cantilevers. A hi

Processing optimization allowed the sol-gel fabrication of 1 mum thick, phase pure perovskite thin films with identical grain size and controlled texture. This made it possible to fabricate stress compensated beams to measure the transverse piezoelectric coefficient over the whole composition range of PbZr1-xTixO3. The highest value of -12.1 C/m(2) was measured for (100)/(001) textured PZT53/47. For (111) textured films the maximum value of -8.7 C/m(2) was found to be in the tetragonal phase field at 55% Ti

Pyroelectric sensor has each pixel's secondary electrode made with no contact with other secondary electrodes. The pyroelectric sensor consists of a series of pixels (12A) with primary (14) and secondary (28) electrodes on opposite surfaces of a thin porou ...

PbZrxTi1-xO3 (x=0.45) and PbxCa1-xTiO3 (PCT) (x=0.75) porous thin films were deposited on platinized silicon wafers by chemical solution deposition route using a polymer as a volatile phase. The introduction of pores creates a matrix-void composite resulting in a high figure of merit for pyroelectric applications. The figures of merit F-v and F-d for PCT films are shown to be as high as 4.8 and 250 muC/m(2) K, respectively. (C) 2002 American Institute of Physics.

Effective transverse piezoelectric coefficient e(31,f) has been measured on (100)/(001) sol-gel Pb(ZrXTi1-X) thin films with compositions between 30% and 45% Zr. A maximum value of 8.07 +/- 0.36 C/m(2) at 40% Zr is found. The influence of the poling field ranging from 50 kV/cm to 250 kV/cm has been evaluated.

Pb(Mg1/3Nb2/3)O-3 (PMN) alkoxide precursor solutions were synthesized and used to prepare thin films by spin coating on TiO2/Pt/TiO2/SiO2/Si substrates. Many parameters like the use of homogeneous and stable precursor solutions and appropriate processing were used to greatly reduce the presence of the nonferroelectric pyrochlore phase. Transmission electron microscopy investigations, dielectric, electrostrictive, and direct current field induced piezoelectric measurements were carried out and have shown tha

Andreas Seifert

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Mechanisms of Pb(Zr0.53Ti0.47)O-3 thin film etching with ECR/RF reactor

Relaxor Pb(Mg1/3Nb2/3)O-3 thin films and their electromechanical properties

Electrical properties and microstructural evolution of porous Pb1-xCaxTiO3 pyroelectric thin films

Thin film pyroelectric arrays as infra-red detectors

Poling of pyroelectric thin films

Microstructural evolution of dense and porous pyroelectric Pb1−xCaxTiO3 thin films

Electromechanical properties of sol-gel derived Ca-modified PbTiO3 films

Preparation and electromechanical properties of Pb(Mg1/3Nb2/3)O-3 thin film

High figure-of-merit porous Pb1-xCaxTiO3 thin films for pyroelectric applications

In-plane piezoelectric coefficient of PZT thin films as a function of composition

{100}-textured, piezoelectric Pb(Zr-x Ti1-x)O-3 thin films for MEMS: integration, deposition and properties

Piezoelectric cantilever microphone for photoacoustic GAS detector

Processing optimization of solution derived PbZr1-xTixO3 thin films for piezoelectric applications

Capteur pyroelectrique ayant entre ses pixels un couplage thermique parasite reduit

Pyroelectric nanoporous films: Synthesis and properties

Effective transverse piezoelectric coefficient e(31,f) of (100)/(001) textured PZT thin films

Relaxor behavior and electromechanical properties of Pb(Mg1/3Nb2/3)O-3 thin films